Capacitor having a feedthrough assembly with a coupling member

ABSTRACT

A flat capacitor includes a case having a feedthrough hole, a capacitor stack located within the case, a coupling member having a base surface directly attached to the capacitor stack and having a portion extending through the feedthrough hole, the coupling member having a mounting hole, a feedthrough conductor having a portion mounted within the mounting hole, and a sealing member adjacent the feedthrough hole and the feedthrough conductor for sealing the feedthrough hole. Other aspects of the invention include various implantable medical devices, such as pacemakers, defibrillators, and cardioverters, incorporating one or more features of the exemplary feedthrough assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a division of application Ser. No.09/706,579, filed on Nov. 3, 2000, the specification of which isincorporated herein by reference.

[0002] This application is related to application Ser. No. 09/706,447,filed on Nov. 3, 2000, now issued as U.S. Pat. No. 6,699,265, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

[0003] The present invention concerns implantable heart monitors, suchas defibrillators and cardioverters, particularly structures and methodsfor capacitors in such devices.

BACKGROUND

[0004] Since the early 1980s, thousands of patients prone to irregularand sometimes life-threatening heart rhythms have had miniature heartmonitors, particularly defibrillators and cardioverters, implanted intheir bodies. These devices detect onset of abnormal heart rhythms andautomatically apply corrective electrical therapy, specifically one ormore bursts of electric current, to hearts. When the bursts of electriccurrent are properly sized and timed, they restore normal heart functionwithout human intervention, sparing patients considerable discomfort andoften saving their lives.

[0005] The defibrillator or cardioverter includes a set of electricalleads, which extend from a sealed housing into the walls of a heartafter implantation. Within the housing are a battery for supplyingpower, monitoring circuitry for detecting abnormal heart rhythms, and acapacitor for delivering bursts of electric current through the leads tothe heart.

[0006] The capacitor can take the form of a flat aluminum electrolyticcapacitor. Flat capacitors include a stack of flat capacitor elements,with each element including one or more separators between two sheets ofaluminum foil. The capacitor elements, each of which has an individualcapacitance (or energy-storage capacity) proportional to the surfacearea of the aluminum foil, are connected together to provide a totalcapacitance. The stack of capacitor elements is housed within analuminum capacitor case which is filled with electrolyte.

[0007] The capacitor includes one or more metal wires, known asfeedthroughs, which connect the capacitor elements to defibrillator orcardioverter circuitry located outside the case. A feedthrough reachesthe outside of the case through a hole in the case called a feedthroughhole. After the capacitor elements are assembled within the capacitorcase and the feedthrough is inserted through the feedthrough hole,manufacturers insulate the feedthrough from the case and seal thefeedthrough hole. This involves, for instance, assembling an insulatingsleeve, a nut, a gasket and/or other hardware around the feedthroughwire.

[0008] Thus, assembling the feedthrough, insulating the feedthrough, andsealing the feedthrough is a complex, time-consuming process.

SUMMARY

[0009] To address these and other needs, the inventors have devised newcapacitor structures and methods. An exemplary capacitor includes a casecontaining a capacitor stack. A coupling member having a base surface isdirectly attached to the capacitor stack. A feedthrough conductor has aportion which extends through a feedthrough hole in the case and into amounting hole in the coupling member. The capacitor includes a sealingmember adjacent the feedthrough hole and the feedthrough conductor forsealing the feedthrough hole.

[0010] One option provides an exemplary feedthrough assembly whichincludes a plug having a hole and a feedthrough conductor mounted withinthe hole. The feedthrough conductor has a diameter approximately equalto or larger than the plug hole diameter, thus sealing the feedthroughhole without requiring any epoxy or excess hardware.

[0011] Among other advantages, the relatively uncomplicated feedthroughstructure of the exemplary capacitor provides for easier manufacturingand more reliable capacitors. Other facets of the invention includevarious implantable medical devices, such as pacemakers, defibrillators,and cardioverters, incorporating one or more features of the novelcapacitors.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIG. 1 is an isometric view of a flat capacitor in accord with oneembodiment of the present invention.

[0013]FIG. 2 is an exploded isometric view of the flat capacitor of FIG.1.

[0014]FIG. 3 is another exploded isometric view of the flat capacitor ofFIG. 1.

[0015]FIG. 4 is a cross-sectional view of the feedthrough assembly ofFIG. 1.

[0016]FIG. 5A is an isometric view of the exemplary feedthrough assemblyof FIG. 1.

[0017]FIG. 5B is a side view of the exemplary feedthrough assembly ofFIG. 1

[0018]FIG. 6 is an isometric view of an exemplary coupling member inaccord with one embodiment of the present invention.

[0019]FIG. 7 is an isometric view of another exemplary coupling memberin accord with one embodiment of the present invention.

[0020]FIG. 8A is an isometric view of another exemplary coupling memberin accord with one embodiment of the present invention.

[0021]FIG. 8B is an isometric view of another exemplary coupling memberin accord with one embodiment of the present invention.

[0022]FIG. 9 is a side view of the feedthrough assembly of FIG. 1.

[0023]FIG. 10 is an exploded isometric view of a flat capacitoraccording to one embodiment of the present invention.

[0024]FIG. 11 is a cross-sectional view of the feedthrough assembly ofFIG. 10.

[0025]FIG. 12 is a cross-sectional side view showing a feedthrough plugaccording to one embodiment.

[0026]FIG. 13 is a schematic view of an exemplary implantable medicaldevice incorporating a capacitor according to the present invention.

DETAILED DESCRIPTION

[0027] The following detailed description, which references andincorporates the figures, describes and illustrates one or more specificembodiments of the invention. These embodiments, offered not to limitbut only to exemplify and teach the invention, are shown and describedin sufficient detail to enable those skilled in the art to practice theinvention. Thus, where appropriate to avoid obscuring the invention, thedescription may omit certain information known to those of skill in theart.

[0028]FIG. 1 shows a flat capacitor 100 in accord with one embodiment ofthe present invention. Capacitor 100 includes a case 101, a feedthroughassembly 103, a terminal 104, and a sealing member 105. In the exemplaryembodiment, case 101 is a D-shaped container manufactured from aconductive material, such as aluminum. In other embodiments, case 101 isrectangular, circular, oval, or other desirable symmetrical orasymmetrical shape. Also, in some embodiments, case 101 is manufacturedfrom a nonconductive material, such as a ceramic or a plastic.

[0029] Case 101 includes a feedthrough hole 107 which is drilled,molded, or punched in a portion of a wall of case 101. Feedthrough hole107 is in part defined by an edge 107 a which outlines the feedthroughhole within case 101. Feedthrough hole 107 provides a passage forconnecting feedthrough assembly 103 to circuitry outside of case 101. Insome embodiments, case 101 includes two or more feedthrough holes forproviding a second or third feedthrough assembly.

[0030] Feedthrough assembly 103 and terminal 104 connect capacitorelements to outside circuitry. In the exemplary embodiment, feedthroughassembly 103 extends through feedthrough hole 107 and is insulated fromcase 101. Terminal 104 is directly connected to case 101. Alternatively,in some embodiments, the capacitor incorporates other connectionmethods, depending on other design factors. In various embodiments, twoor more insulated feedthrough assemblies are employed.

[0031] In the exemplary embodiment, sealing member 105, such as anepoxy, is deposited around feedthrough hole 107 and feedthrough assembly103 to insulate feedthrough assembly 103 from case 101 and to seal anelectrolyte within the case. An exemplary epoxy is a two-part epoxymanufactured by Dexter Hysol. This includes a casting resin compound(manufacturer No. EE 4183), a casting compound (manufacturer No. EE4215), and a hardener (manufacturer No. HD 3404). The exemplary two-partepoxy is mixed in a ratio of hardener=0.055*casting resin. The mixtureis cured at 0.5 hours at 60 degrees Celsius or 1.5 hours at roomtemperature. Another exemplary epoxy is a UV cure epoxy such asmanufactured by Dymax, Inc., which can be cured using an Acticure(manufactured by GenTec) ultraviolet curing system at 7 W/cm² at adistance of 0.25″ for approximately 10 seconds.

[0032] In one embodiment, the sealing member provides a non-hermeticseal. In one embodiment, the sealing member includes an elastic plugwhich will be discussed in further detail below.

[0033]FIGS. 2 and 3 show exploded views of exemplary capacitor 100.Capacitor 100 includes a capacitor stack 202 mounted within an internalcavity 212. The exemplary capacitor stack 202 includes a plurality ofcapacitor modules or elements 205 a, 205 b, 205 c, . . . , 205 n. Eachof elements 205 a-205 n includes a cathode, an anode, and a separatorbetween the cathode and the anode.

[0034] Each anode includes one or more anode members in a stack. Theseanodes and cathodes are foil structures and can be made from aluminum,tantalum, hafnium, niobium, titanium, zirconium, and combinations ofthese metals. A major surface of each anode foil is roughened toincrease its effective surface area. This increases the capacitiveeffect of the foil with no relative increase in volume. However, none ofthe embodiments are limited to any particular foil composition or classof foil compositions.

[0035] The separators include one or more electrolyte impregnatedseparators between each anode and each cathode. In the exemplaryembodiment, each separator consists of two kraft papers impregnated withan electrolyte. The electrolyte can be any suitable electrolyte for anelectrolytic capacitor, such as an ethylene-glycol base combined withpolyphosphates, ammonium pentaborate, and/or an adipic acid solute.Other embodiments incorporate different numbers and arrangements ofanodes, cathodes, and separators.

[0036] In the exemplary embodiment, each cathode of capacitor stack 202is connected to the other cathodes and to conductive case 101. Terminal104 is attached to case 101 to provide a cathode connection to outsidecircuitry. In some embodiments, the cathode is coupled to a feedthroughconductor extending through a feedthrough hole.

[0037] In the exemplary embodiment, each anode is connected to the otheranodes of the capacitor. Attached to the anode of each capacitor element205 a-205 n is a conductive tab or connection member 201. In oneembodiment, each connection member 201 includes an edge face 215 whichis substantially perpendicular to the major surface of the anodes. Edgeface 215 provides a conductive surface for connecting each capacitorelement 205 a-205 n to feedthrough assembly 103. The anode connectionmembers 201 are welded or crimped together and are coupled tofeedthrough assembly 103 for electrically connecting the anode tocircuitry outside the case. In some embodiments, the cathode is coupledto a feedthrough assembly and the anode is connected to the case. Inother embodiments, both the anode and the cathode are connected tofeedthroughs.

[0038] In one embodiment, connection members 201 are edge-welded to eachother as discussed in U.S. patent application Ser. No. 09/706,518, filedNov. 3, 2000, now issued as U.S. Pat. No. 6,687,118, which isincorporated herein by reference in its entirety. Edge-welding theconnection members provides a flat connection surface 216, whichincludes one or more edge faces 215 of connection members 201. In someembodiments, connection members 201 are crimped, soldered, and/orconnected by an electrically conductive adhesive.

[0039] In the exemplary embodiment, feedthrough assembly 103 includestwo members, a feedthrough wire or conductor 203 and a coupling member204. Coupling member 204 is attached to capacitor stack 202 atconnection surface 216, and feedthrough conductor 203 is attached tocoupling member 204. In the exemplary embodiment, coupling member 204partially extends through feedthrough hole 107.

[0040] Feedthrough conductor 203 is a conductive member which caninclude material such as nickel, gold plated nickel, platinum, aluminum,or other conductive metal. Feedthrough conductor 203 has a proximal endportion 217 attached to coupling member 204 and a distal end portion 218for attaching to circuitry outside the case, such as defibrillator orcardioverter circuitry. In the exemplary embodiment, feedthroughconductor 203 has a diameter of approximately 0.016″ (0.4064 mm).However, other embodiments have feedthrough conductors of differentdiameters and/or non-circular cross-sections.

[0041]FIG. 4 shows a cross-sectional side view of details of oneembodiment of feedthrough assembly 103 and its connection to connectionmembers 201. As discussed above, in the exemplary embodiment, the edgefaces 215 of each connection member 201 form a substantially flatconnection surface 216. In the exemplary embodiment, coupling member 204is directly attached to connection members 201 at surface 216.

[0042] In the exemplary embodiment, coupling member 204 is a high-purityaluminum member which is able to withstand the high voltages generatedwithin the capacitor case. In other embodiments it is made from anotherconductive material compatible with the capacitor stack. Coupling member204 includes a base 404 and a holding tube 407. On one side of base 404is a planar surface 405 for attaching to the planar surface 216presented by edge-welded connection members 201.

[0043]FIG. 6 shows additional details of exemplary base 404. In theexemplary embodiment, base 404 is substantially rectangular having apair of opposing rounded or curved ends 602 and 604.

[0044] Referring again to FIG. 4, in the exemplary embodiment, couplingmember 204 is situated so that surface 405 abuts connection membersurface 216. Coupling member 204 is laser welded using a butt-weld tosurface 216 of connection members 201. Alternatively, coupling member204 is attached using other means. Butt-welding coupling member 204directly to connection members 201 provides an optimal electricalconnection between capacitor stack 202 and the feedthrough assembly.Moreover, it also provides for a compact capacitor since very little, ifany, space is wasted between capacitor stack 202 and feedthroughassembly 103. Also, since coupling member 204 is directly attached tocapacitor stack 202, it helps support feedthrough conductor 203 while asealing member 105, such as an epoxy, is applied to the feedthrough holearea.

[0045] Holding tube 407 is located on the opposing side of base 404 fromsurface 405. Tube 407 is a cylindrical member having an outer diameterdimensioned to fit within feedthrough hole 107. Tube 407 has a mountingsection such as mounting hole 401 defined in part by an inner surface402 of holding tube 406 which is generally perpendicular to base surface405. Hole 401 is located down an axial portion of the tube.

[0046] Mounting section or hole 401 is for receiving proximal endportion 217 of feedthrough conductor 203. The surface of feedthroughconductor 203 contacts inner surface 402. In the exemplary embodiment,hole 401 is approximately 0.016″ (0.4064 mm) in diameter. Alternatively,its diameter can conform with the size of conductor 203 so thatfeedthrough conductor 203 can matably fit within the hole. In theexemplary embodiment, coupling member 204 has a height 204 h ofapproximately 0.085″ (2.519 mm). Other embodiments range from 0.050″ to0.100″ or higher. Some embodiments provide a height of greater than0.100″.

[0047]FIGS. 5A and 5B show an exemplary attachment of feedthroughconductor 203 to coupling member 204. In the exemplary embodiment,feedthrough conductor 203 and coupling member 204 are connected at acrimp 502. Alternatively, they are welded, soldered, glued orinterference fit together, as will be discussed below. Exemplary crimp502 compresses inner surface 402 (see FIG. 4) of tube 407 intomechanical and electrical connection with the surface of portions offeedthrough conductor 203. In the exemplary embodiment, a double crimpis employed. In some embodiments, a single crimp, double crimp, triplecrimp or more are used.

[0048] In the exemplary embodiment, inner surface 402 of coupling member204 is a curved surface defining an annular connection member. Crimp 502compresses and deforms opposing surfaces of annular inner surface 402 tocontact conductor 203. In the exemplary embodiment, the opposingsurfaces of inner surface 402 are separated by a first distance prior tobeing crimped and separated by a second distance, smaller than the firstdistance, after being crimped.

[0049]FIG. 7 shows another exemplary coupling member 700. Member 700includes a base 701 and a holding tube 702. Base 701 is acircular-shaped base. In the exemplary embodiment, base 701 has adiameter of approximately 0.050″ (1.27 mm). In one embodiment (notshown), the base is square shaped.

[0050]FIG. 8A shows another exemplary coupling member 800. Member 800does not include a base. In the exemplary embodiment, hole 401 runscompletely through holding tube 802. In the exemplary embodiment, oneend of tube 802 has a connection surface and is attached to surface 216of connection members 201. A second end of tube 802 receives feedthroughconductor 203.

[0051]FIG. 8B shows another exemplary coupling member 850. Member 850does not include a base. In the exemplary embodiment, hole 401 runs onlypartially through a holding tube 852. In the exemplary embodiment, oneend of member 850 has a connection surface and is attached to surface216 of connection members 201. An end of tube 802 receives feedthroughconductor 203.

[0052]FIG. 9 shows a side view of feedthrough assembly 103 in whichfeedthrough conductor 203 is coupled to coupling member 204 at one ormore arc percussion welding areas, such as areas 982 a and 982 b. Anexemplary arc percussion welding machine is manufactured by Morrow TechIndustries of Broomfield, Colo. In this embodiment, the conductor 203and coupling members are not crimped together. However, some embodimentsinclude both welding and crimping.

[0053]FIG. 10 shows an exploded view of capacitor 100 having a sealingmember such as a plug 106 according to one embodiment of the presentinvention. Plug 106 is insertable into feedthrough hole 107 of case 101.In one embodiment, plug 106 has an outer diameter which is larger thanthe diameter of feedthrough hole 107, and the manufacturer inserts itwithin hole 107 in an interference fit. When plug 106 is located withinfeedthrough hole 107, the plug seals feedthrough hole 107 andelectrically insulates feedthrough assembly 103 from case 101. In someembodiments plug 106 includes one or more flanges, which will bediscussed below.

[0054]FIG. 11 shows a cross-sectional view of plug 106 assembled withcapacitor case 101. The present example show coupling member 204attached to capacitor stack 202. However, in other embodiments plug 106can also be used in capacitors having other types of feedthroughassemblies. In one embodiment, plug 106 electrically insulates case 101from coupling member 204. Coupling member 204 has a first end 1115located in the interior of case 101 and coupled to capacitor stack 202.Coupling member 204 also includes a second end 1111 located exterior tocase 101 for connecting to circuitry, such as defibrillator, or otherimplantable medical device circuitry. In one embodiment, coupling member204 has a feedthrough terminal attached thereto.

[0055] In this embodiment, plug 106 is a double-flanged plug. Plug 106includes a first flange 108. First flange 108 includes a first surface108 a which faces the inner surface of case 101. When the capacitorbegins to become pressurized, pressure against a second surface 108 bforces first surface 108 a against the case. Thus, flange 108 creates aseal against the inner surface of case 101.

[0056] In this embodiment, plug 106 includes a second flange 109. Flange109 includes a surface which faces the outer surface of case 101.

[0057] Plug 106 also includes a plug portion 110 which is locatedbetween and defined by first flange 108 and second flange 109. Portion110 has a smaller diameter than either flange 108 and/or 109. Case edge107 a confronts plug 106 at portion 110. In this embodiment, portion 110has a normal, unstressed outer diameter approximately equal to thediameter of feedthrough hole 107. In some embodiments, the unstressedouter diameter is larger than the diameter of feedthrough hole 107. Insome embodiments, the unstressed outer diameter is smaller than hole107. As one example, in this embodiment flange 108 has a diameter ofapproximately 0.080 inches and portion 110 has a diameter ofapproximately 0.060 inches.

[0058] Plug 106 also includes a central passage or hole 1102. In oneembodiment, hole 1102 is axially located through the center of plug 106and has an unstressed diameter 1102 d which is smaller than or equal toa diameter 103 d of a portion of feedthrough member 103 which is mountedwithin hole 1102. In various embodiments, diameter 1102 d may range fromapproximately 0.015 inches to approximately 0.033 inches. In otherembodiments, diameter 1102 d is smaller than 0.015 inches. In someembodiments it is greater than 0.033 inches. Other embodiments vary thehole size depending on the size of the feedthrough conductor used. Insome embodiments, when a feedthrough member such as coupling member 204is inserted through hole 1102, an interference fit seal is developedbetween the feedthrough member and the plug. In other embodiments,hydrogen gas can escape along the feedthrough member/plug 106 border.

[0059] In one embodiment, plug 106 is made from a compressible, elasticmaterial such as rubber, plastic, thermoplastic, or other elastic orelastomeric material. In one embodiment, when plug 106 is mounted withinfeedthrough hole 107 and feedthrough member 103 is mounted within hole1102, plug portion 110 is compressed between assembly 103 and edge 107 aof feedthrough hole 107 and the plug exerts a radial force on edge 107 aof the feedthrough hole. This forces or compresses plug 106 into aninterference or compression fit between feedthrough hole edge 107 a andmember 204, thus helping to seal electrolyte solution within case 101.In other embodiments, the diameter of portion 110 is smaller than hole107 and an interference fit between feedthrough hole edge 107 a andmember 204 is not created.

[0060] In one embodiment, as noted above, flange 108 provides a sealingmeans for helping seal electrolyte within the case. Accordingly, in someembodiments, when the diameter of portion 110 is smaller than hole 107and an interference fit between feedthrough hole edge 107 a and member204 is not created, only flange 108 provides a sealing means betweencase 101 and plug 106. Advantageously, the seal or seals are formedautomatically. Thus, in one embodiment, assembling and tightening ascrew or other extraneous hardware is not required to seal thecapacitor.

[0061] In one embodiment, second flange 109 provides support formounting plug 106 within hole 107. For instance, when plug 106 ismounted in hole 107, flanges 108 and 109 each help hold plug 106 inplace once it is mounted, but before the coupling member 204 is insertedthrough hole 1102. This aides the manufacturing process.

[0062] In one embodiment second flange 109 includes a tapered sectionwherein an outer portion 109 a of flange 109 has a smaller diameter thanan inner portion 109 b. The tapered shape of flange 109 aids ininserting plug 106 into hole 107. Some embodiments omit the taperedshape and flange 109 has a uniform outer diameter. Other embodimentsprovide a tapered shape for first flange 108. Other embodiments providetapered sections on both flanges.

[0063] In this embodiment, flange 108 has a larger diameter than flange109. In some embodiments, the two flanges have substantially equaldiameters. In further embodiments, flange 109 has a larger diameter thanflange 108.

[0064] Some embodiments omit either or both of flanges 108 and 109. Forinstance, in some embodiments plug 106 has a generally cylindricalshape. In other embodiments, plug 106 has an hour-glass shape or othershape which closely fits within feedthrough hole 107. In someembodiments, plug 106 is a mass of elastic material with a dimensionapproximately equal to or larger than the width of feedthrough hole 107.

[0065] In one embodiment, plug 106 seals the electrolyte withincapacitor case 101, but it does not provide a hermetic seal. Hydrogen iscreated during consumption of water from the electrolyte and continuesto be formed throughout the life of the capacitor. This can cause ahermetically sealed capacitor case to bulge outward from the hydrogengas production within, thus risking long-term device reliability due toshorting.

[0066] Accordingly, in one embodiment plug 106 permits out-gassing ofhydrogen gas, thus alleviating any problems. For instance, in oneembodiment, flange 108 creates a seal to the inner wall of the case 101.A pathway for the gas to escape is then present along the border betweencoupling member 204 and plug 106.

[0067]FIG. 12 shows a cross-sectional side view of a plug 120 accordingto one embodiment. Plug 120 includes one or more features of plug 106and discussion of unnecessary details will be omitted. Plug 120 includesa first flange 128, a second flange 129, and a portion 130 between thetwo flanges 128 and 129. In one embodiment, plug 130 includes a hole132. Hole 132 has a sealing section such as a narrow section 132 b,which is located between two nominal diameter sections 132 a and 132 b.Other embodiments omit section 132 b or move it to either end, therebyomitting sections 132 a or 132 b.

[0068] In one embodiment, narrow section 132 b provides an O-ring typeinterference fit for a feedthrough member such as coupling member 204.In this embodiment, narrow section 132 b is generally located withinsecond flange 129. Other embodiments locate the narrow section withincentral portion 130. Other embodiments locate the narrow section withinfirst flange 128. By way of example, in one embodiment, the nominaldiameters of sections 132 a and 132 c is approximately 0.032 inches, andthe diameter of narrow section 132 b is 0.026 inches.

[0069] Referring again to FIG. 10, one method of assembling a capacitorhaving a plug 106 is as follows. Plug 106 is inserted into feedthroughhole 107 of case 101. In one embodiment, plug 106 includes adouble-flange construction which helps hold the plug in place once it ismounted. Feedthrough assembly 103 is attached to capacitor stack 202 andinserted through inner hole 1102 of plug 106 while capacitor stack 202is placed within the cavity of case 101. An interference fit betweenplug 106 and feedthrough 103 and between case 101 and plug 106 arecreated. Thus, a seal is formed between the interior of case 101 and theexterior of case 101.

Exemplary Embodiment of Implantable Defibrillator

[0070]FIG. 13 shows one of the many applications for capacitorsincorporating one or more teachings of the present invention: a genericimplantable heart monitor 1300. As used herein, implantable heartmonitor includes any implantable device for providing therapeuticstimulus to a heart muscle. Thus, for example, the term includespacemakers, defibrillators, cardioverters, congestive heart failuredevices, and combination and permutations thereof.

[0071] Heart monitor 1300 includes a lead system 1303, which afterimplantation electrically contact strategic portions of a patient'sheart. Shown schematically are portions of monitor 1300 including amonitoring circuit 1302 for monitoring heart activity through one ormore of the leads of lead system 1303, and a therapy circuit 1301 fordelivering electrical energy through one or more of the leads to aheart. Monitor 1300 also includes an energy storage component, whichincludes a battery 1304 and incorporates at least one capacitor 1305having one or more of the features of the exemplary capacitors describedabove.

[0072] In addition to implantable heart monitor and other cardiac rhythmmanagement devices, one or more teachings of the present invention canbe incorporated into photographic flash equipment or other devices usingflat or cylindrical capacitors. Indeed, these teachings of the inventionare pertinent to any application where high-energy, high-voltage, orspace-efficient capacitors are desirable.

Conclusion

[0073] In furtherance of the art, the inventors have devised a capacitorwhich includes, in an exemplary embodiment, a coupling member attachedto a capacitor stack of the capacitor, a feedthrough conductor attachedto the coupling member and extending through the feedthrough hole of thecapacitor, and means for sealing the feedthrough hole. One embodimentprovides a feedthrough assembly which includes a plug having a hole anda feedthrough conductor mounted within the hole. The feedthroughconductor has a diameter approximately equal to or larger than the plughole diameter, thus sealing the feedthrough hole without requiring anyexcess hardware. Among other advantages, the relatively uncomplicatedfeedthrough structure of the exemplary embodiments provides for easiermanufacturing and more reliable capacitors.

[0074] The embodiments described above are intended only to illustrateand teach one or more ways of practicing or implementing the presentinvention, not to restrict its breadth or scope. The actual scope of theinvention, which embraces all ways of practicing or implementing theteachings of the invention, is defined only by the following claims andtheir equivalents.

1-21. (canceled)
 22. A capacitor comprising: a case having a feedthroughhole; an capacitor stack within the case; an elastic plug mounted withinthe feedthrough hole, the plug having an inner hole; and a feedthroughconductor coupled to the capacitor and extending through the plug innerhole; wherein the plug electrically insulates the feedthrough conductorfrom the case.
 23. The capacitor of claim 22, wherein the elastic plugincludes a flange confronting an inner surface of the case.
 24. Thecapacitor of claim 22, wherein the capacitor comprises a flat capacitor.25. The capacitor of claim 22, wherein the feedthrough conductor isdirectly attached to the capacitor stack.
 26. The capacitor of claim 22,wherein the plug has one inner hole.
 27. The feedthrough assembly ofclaim 22, wherein the plug includes a first flange located inside thecase and a second flange located outside the case.
 28. The feedthroughassembly of claim 22, wherein the feedthrough conductor comprises analuminum coupling member having a first end extending from a first endof the plug and having a second end extending from a second end of theplug and directly coupled to an active element of the flat capacitor.29. An implantable medical device comprising: one or more leads forsensing electrical signals of a patient or for applying electricalenergy to the patient; a monitoring circuit for monitoring heartactivity of the patient through one or more of the leads; and a therapycircuit for delivering electrical energy through one or more of theleads to a heart of the patient, wherein the therapy circuit includesone or more capacitors, each capacitor comprising: a case having afeedthrough hole; a capacitor stack located within the case; a couplingmember having a base surface directly attached to the capacitor stack,the coupling member having a mounting hole; a feedthrough conductorhaving a portion extending into the mounting hole; and a sealing memberadjacent the feedthrough hole for sealing the feedthrough hole.
 30. Theimplantable medical device of claim 29, wherein the coupling membercomprises a base abutting a surface of the capacitor stack.
 31. Theimplantable medical device of claim 30, wherein the capacitor stackincludes two or more connection members, each connection member havingan edge face, the surface of the capacitor stack comprises at least oneof the edge connection member faces.
 32. The implantable medical deviceof claim 29, wherein the sealing member comprises an elastic plugmounted within the feedthrough hole, the elastic plug having an innerhole, the feedthrough member mounted within the inner hole.
 33. Theimplantable medical device of claim 32, wherein the elastic plug isinterference fitted within the feedthrough hole.
 34. A method forassembling a capacitor, the method comprising: crimping a feedthroughconductor to a coupling member; attaching the coupling member to acapacitor stack of the flat capacitor; inserting the capacitor stackinto a capacitor case so that the feedthrough conductor passes through afeedthrough hole in the capacitor case; and sealing the feedthroughhole.
 35. The method of claim 34, wherein attaching the coupling membercomprises butt-welding the coupling member to a flat connection surfaceof the active element.
 36. The method of claim 34, wherein sealing thefeedthrough hole comprises non-hermetically sealing the feedthrough holeby depositing an epoxy around the feedthrough hole.
 37. The method ofclaim 34, wherein sealing the feedthrough hole comprises mounting anelastic insert within the feedthrough hole and inserting a feedthroughconductor through the elastic insert.
 38. A method of sealing afeedthrough hole of a capacitor, the method comprising: mounting anelastic insert within the feedthrough hole; and inserting a feedthroughconductor through the elastic insert.
 39. The method of claim 38,wherein the elastic insert has a flange for holding the elastic insertwithin the feedthrough hole.
 40. A method of manufacturing a capacitorhaving a capacitor case having a feedthrough hole, the methodcomprising: mounting an elastic plug within the feedthrough hole so afirst flange of the plug is on an inside of the case and so that asecond flange of the elastic plug is on an outside of the case; directlyattaching a feedthrough conductor to a capacitor stack; and insertingthe feedthrough conductor through a hole in the elastic plug.
 41. Themethod of claim 40, wherein the feedthrough conductor has an outerdiameter approximately equal to or larger than an unstressed diameter ofthe hole in the elastic plug.